Question: Solve for $x$ and $y$ using substitution. ${2x-y = 5}$ ${y = -x+1}$
Since $y$ has already been solved for, substitute $-x+1$ for $y$ in the first equation. ${2x - }{(-x+1)}{= 5}$ Simplify and solve for $x$ $2x+x - 1 = 5$ $3x-1 = 5$ $3x-1{+1} = 5{+1}$ $3x = 6$ $\dfrac{3x}{{3}} = \dfrac{6}{{3}}$ ${x = 2}$ Now that you know ${x = 2}$ , plug it back into $\thinspace {y = -x+1}\thinspace$ to find $y$ ${y = -}{(2)}{ + 1}$ $y = -2 + 1$ $y = -1$ You can also plug ${x = 2}$ into $\thinspace {2x-y = 5}\thinspace$ and get the same answer for $y$ : ${2}{(2)}{ - y = 5}$ ${y = -1}$